An electronic device such as a smart phone, a tablet type information terminal, or a mobile phone has rapidly spread in recent years. FIG. 11 is an appearance perspective view of an electronic device, a smart phone as an example. An electronic device 200 has various functions besides a telephone call function. Examples of the functions include a map display function using GPS. A map display function using map information and GPS signals stored in a hard disk or an IC memory allows a user to obtain exact position information on a display 300 provided on the electronic device. At this time, when information on a direction to which the user faces is reflected in the map display function, an electronic compass 260 including a geomagnetic sensor is used. The electronic compass 260 provides direction information based on a direct-current magnetic field according to geomagnetism using a geomagnetic sensor such as a hole device and a magnetoresistance effect element.
A position detecting device as an inputting device in which a user can easily put operation information and character information is employed for the electronic device 200 such as a smart phone or a tablet.
The position detecting device is obtained by combining a pen type device 210 for dictating a position with a device referred to as a sensor substrate for detecting a position, for example. A specific example of a position detecting device is shown in FIG. 12. A pulse signal having a frequency of 500 kHz is applied to a coil group 340 including sensor coils for X and Y directions provided on the sensor substrate 350 side from a coil provided in the pen type device 210. Position information is obtained by an electromotive force generated in the coil group 340 according to the principle of electromagnetic induction. In the electronic device 200, the sensor substrate 350 is provided below a display panel 305, and various softwares are coordinated with the position information on the display, which provides easy input of information to the electronic device 200. A magnetic body member 360 as a magnetic yoke or a magnetic shield is disposed so as to cover the whole lower part of the display panel 305 between the sensor substrate 350 and a circuit substrate 370.
In another constitution, a sensor substrate 350 in which a coil group 340 which cannot be visually confirmed is formed on a light transmissive substrate may be provided on the upper side of a display panel 305, and a magnetic body member 360 may be disposed between the display panel 305 and a circuit substrate 370.
A magnetic body member may be disposed as a magnetic shield in an electronic device irrespective of the presence or absence of a sensor substrate.
Since an electronic compass uses small geomagnetism, the electronic compass is known to be apt to be influenced by a magnetic noise generated by a part having a magnet such as a speaker. However, the magnetic body member also is recognized to largely influence the direction information of the electronic compass. Specifically, a direct-current magnetic field according to geomagnetism is deflected near the magnetic body member. For this reason, when the electronic compass is disposed near the magnetic body member, the error of the direction information of the electronic compass is increased, it is confirmed that there are cases where the right direction is not obtained.
Patent Document 1 proposes that a magnetic body member itself having a low magnetic permeability is produced by forming a magnetic material such as an amorphous metal in a powder state, and hardening the magnetic material by a resin or forming a coating material containing the magnetic material in order to address the problem. When the magnetic body member has a low magnetic permeability, a disordered magnetic flux near the magnetic body member is also relatively decreased. Therefore, even when an electronic compass is positioned close to the magnetic body member, the error of direction information to be obtained can be decreased.
Patent Document 2 describes that a powdered magnetic material is used in a state where the magnetic material is dispersed in a rubber or a resin for a magnetic body member used for a sensor substrate as in Patent Document 1.